1. Field of Invention
This invention relates to improvements in or relating to mass flow measuring devices. In particular, the invention relates to improvements in such devices in which streamline flow ("bulk flow") of bulk material is established on a sensor member. Such apparatuses are of particular use in vehicles such as combine harvesters and forage harvesters. In such vehicles it is desirable to provide data on the mass flow rate of grains of crop passing between the grain elevator and the bubble up auger for temporary storage in the grain tank of the vehicle.
2. Description of Prior Art
Mass flow measuring devices are also employed in stationary installations such as hoppers, silos, conveying machinery, and various kinds of manufacturing and medical apparatuses.
Bulk flow may embrace the flow of bulk grain and chemicals in transport vehicles; the flow of powders and of materials of larger particle size such as fruit, vegetables, coal, minerals and ores; and even the flow of liquids of high viscosity. In general terms, bulk flow of material may be regarded as any flow of matter in contact with a surface, in which the effects of friction between the surface and the material usually influence the maximum flow rate, and in which the matter exhibits free flow behaviour.
Our co-pending U.S. patent application Ser. Nos. 09/005,094 and 09/005,095 disclose sensor members for use in bulk flow measuring apparatuses, in which one or more manufacturing parameters of the sensor members are optimised in order to minimise the effects, on the measured flow rates, of changes in the coefficient of friction between the bulk material and a sensor surface. Such optimisation of manufacturing parameters is of particular benefit in harvesting machinery and crop conveyors, since some characteristics (such as the moisture content) of the bulk material can vary over time, for example during harvesting operations.
Although the apparatuses in application Ser. Nos. of 09/005,094 and 09/005,095 represent significant improvements in the field of mass flow measurement, the inventor has surprisingly discovered that it is possible to make further improvements in mass flow measurement apparatuses.
Broadly stated, the invention relates to apparatuses and methods for measuring two measurable quantities resulting from bulk flow on a sensor member, and deriving from the measured values one or more characteristics of the flow, such characteristics being optionally either independent of or dependent on changes in the coefficient of friction between the bulk material and the sensor surface.